With all good BS some of it is just that.
The 2000 750iL is not ten year old technology. It is at most 2-5 year technology. if you wish a display of servicing such technology try to get someone to work on a ten year old 750il. There isn't a more unpopular car to diagnose than the early 12cyl. Dealer techs will run if one comes in the door.
I personally drive a E39 540i. I do that because it is twice the driving car of a 750iboat. Faster stops, handling is no comparison.
I will probably sell my BMW this year as the model is changing and its financially right. I will probably try a v8 "E" class as I'm not into boats of any Marque. Service doesn't matter to me as my company pays the bills (and does the work of course), but both my ownership and my shop experience says that repairs on the similar cars: C versus E46, E versus E39 and S versus E38/65 will have the BMW in the shop more and costing lots more.
When I bought my BMW I planned to keep it 6 months. I had just gottem BMW diagnostic software and wanted a "guinny pig". I have loved the car but it sure ain't a MB when it comes to service.
Bosch Master, ASE Master, L1
33 years MB technician